Conventionally, an optical-disk recording-reproduction apparatus has been used for recording and reproducing, for example, digital video information, that is, consecutive digital information. In such an apparatus, for example, as illustrated in FIG. 6, an optical disk 1 is used as a recording medium, whereon information tracks in the shape of spirals are formed discontinuously with each other.
This optical disk is provided with the first spiral information track 26 and the second spiral information track 27, both of which are the information tracks in the shape of spirals. For example, the CLV (Constant Linear Velocity) system is adopted for its recording format.
Moreover, for example, as illustrated in FIG. 9, recording and reproducing operations are available in the above-mentioned apparatus. Upon recording, analog video information is inputted through an input terminal 124, and is converted into digital video information in an A/D converter 114.
The digital video information, made through the conversion, is inputted to an information-compression processing circuit 120. In circuit 120, an information-compressing operation is carried out, wherein, for example, an original of data, approximately 160M bps (bit per second), which has been converted to digital video information of the current television signal (NTSC system), is compressed into a compressed amount of data, approximately 5M bps.
The information, thus compressed, is further converted into a form suitable for recording in a recording-data processing circuit 111, and is applied to a coil 104 through a coil driver 105. Thus, the coil 104 applies a modulated magnetic field corresponding to the recording information to an optical disk 1.
Meanwhile, upon receipt of an instruction from a controller 116, a laser driver 106 allows an optical pickup 103 to project a light beam of high power onto the optical disk 1, and the temperature of the optical disk 1 is thus raised locally so as to allow desired information to be recorded thereon.
Additionally, absolute addresses are preliminarily recorded on the optical disk 1 as prior information, and the information obtained through the optical pickup 103 is inputted to a prior-information detection circuit 108 through the reproduction amplifier 107, and part of the information is directed to a CLV circuit 110. In accordance with the information thus inputted, CLV control is executed so that a spindle motor 102 provides a constant linear velocity at a position on the optical disk 1 to which the light beam is being projected.
Further, part of the information from the prior-information detection circuit 108 is also inputted to an absolute-address detection circuit 109, thereby allowing the controller 116 to have the positional information of the optical pickup 103.
Upon reproduction, the optical pickup 1030 is allowed to access a recording area containing information in question. Thus, the information, which was recorded on the optical disk 1, is read out by the optical pickup 103, and directed to a reproduced-data processing circuit 112 through a reproduction amplifier 107.
The reproduced-data processing circuit 112 converts the inputted information into compressed digital information that is a form prior to a recording-data processing, and sends it to an information-decompression processing circuit 121. The digital video information, decompressed in the information-decompression processing circuit 121, is converted into analog video information in the D/A converter 115, and released from an output terminal 125.
Instructions as to the recording and reproduction are entered through an operation section 117, and converted into control signals for various sections in the controller 116. Further, the current positional information and operational state of the optical pickup 103 are displayed on a display section 118 under control of the controller 116.
Here, in the case of recording or reproducing digital information on or from the optical disk 1 by using the optical-disk recording-reproduction apparatus having the above-mentioned arrangement, since the first and second spiral information tracks are formed on the optical disk 1 discontinuously with each other, as shown in FIG. 6, the information recording or reproducing operation is interrupted when the operation is executed over the respective tracks. For example, while the optical pickup 103 moves from the first spiral information track 26 to the second spiral information track 27, the information recording or reproducing operation is interrupted.
In other words, since the optical pickup 103 records or reproduces digital information on or from the optical disk 1 in real time, a period during which the optical pickup 103 is moving from the first spiral information track 26 to the second spiral information track 27 on the optical disk 1 is regarded as an accessing operation period, wherein it is this makes it impossible to conduct the recording or reproducing operation.
For example, if one information track enables a recording or reproducing operation corresponding to video information of 30 minutes, the optical disk 1 having two tracks, that is, the first and second spiral information tracks 26 and 27, are supposed to provide a recording or reproducing operation of 30.times.2 minutes. However, since the respective tracks are formed discontinuously with each other, it is not possible to conduct the recording or reproducing operation for video information of 60 minutes continuously without interruptions.
The problem is that it is not possible to conduct a recording or reproducing operation continuously without interruptions with respect to a plurality of information tracks formed into spiral shapes discontinuously with one another.